There is a need for lighting apparatus for a variety of general lighting purposes which is low-cost and energy-efficient. In the field of lighting, many different types of light sources have been developed. Recently, LED light sources involving multi-LED arrays, each with a large number of LED packages, have been developed as a means of bringing the many advantages of LED lighting—LED efficiency and long life—into the general illumination field. In particular, such LED light fixtures have been developed for use in outdoor settings, including by way of example lighting for parking lots, roadways, display areas and other large areas.
LED light sources are energy-efficient, and advances in LED technology are providing even greater efficiencies over time. One important aspect of LED light fixtures is the so-called secondary lensing that directs light received from LED light sources. Secondary lenses, which receive and direct light from LED light sources, are of significant importance to LED light fixtures in many ways.
Secondary lenses play a major role, of course, in the direction of light from a light fixture, and so determine the degree, spread and orientation of illumination, and overall optical efficiency. The forming and shaping of secondary lenses are typically important considerations with respect to the usefulness of an LED fixture and play a significant role in overall product cost. Improvements in secondary lenses, their optical capabilities, and their manufacture are important considerations in the field of LED light fixtures.
LED light fixtures for a wide variety of both specific and general lighting applications typically have a plurality of LED light sources, usually positioned in spaced relationship to one another on a board (e.g., a circuit board), and a secondary lens is aligned with each LED light source. One such configuration is disclosed in copending U.S. patent application Ser. No. 13/843,928 (Raleigh et al.), titled “Multi-layer Polymeric Lens and Unitary Optic Member for LED light Fixtures and Method of Manufacture.” Such document discloses a unitary optic member for directing light from a plurality of LED light sources on a board beneath the optic member, the optic member having a plurality of lens portions surrounded by and interconnected by a non-lens portion. The optic member of such document includes a first molded polymeric layer forming the non-lens portion and an outermost layer of each of the lens portions, and a second molded polymeric layer overmolded onto the first polymeric layer within pocket-spaces corresponding to each lens portion. One aspect of the invention disclosed in such document is a multi-layer polymeric lens for directing light from an LED light source, the lens defining a lens optical footprint and at least one of the polymeric layers being less than coextensive with the footprint.
As LED lighting becomes more widespread within the lighting marketplace, there is a continuing need to simplify manufacturing and reduce the number of components within LED light fixtures and fixture components. One way to simplify manufacturing and reduce cost and components is to combine the functions of two or more components into a single component. Another is to utilize materials in a way which takes advantage of the best attributes of each material while at the same time eliminating their less-desirable properties. The present invention utilizes such combination of functions and best attributes to provide a unique LED lensing arrangement for lighting fixtures.
It is an object of the present invention to provide an LED lensing arrangement which combines the best attributes of (1) rigid light-transmissive materials such as optical-grade thermoplastic or glass and (2) less rigid optically-clear polymeric materials, such as liquid silicone rubber (LSR), which are pourable and of low enough viscosity upon formation to allow for specific detailed lens-portion shapes that are maintained during product usage despite the presence of heat and moisture.
Stated differently, it is an object of the invention to provide a multi-material LED lensing arrangement which avoids some of the disadvantages of certain materials when used separately, and to provide an LED lensing arrangement that is moldable in a wide variety of shapes for a wide variety of light-directing purposes. Other objects include to reduce cycle times in the component manufacture, to increase dimensional replication of such components, to increase optical efficiency, to increase photometric accuracy, to increase production throughout rates, and to lower overall cost.
These and other objects of the invention will be apparent from the following descriptions and from the drawings.